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module Ch1 exposing ( getCommonFactors )
import String as S
import List as L
import Maybe as Mb
getCommonFactors : Int -> Int -> Result String (List Int)
getCommonFactors m n =
if L.all (\x -> x < 0 ) [m, n]
then Err "" -- probably initial state or equivalent to.
else if L.any(\x -> x < 1) [m, n]
then Err "Please input all the strings !!!"
else
case commonFactors [m, n] of
[] -> Err "invalid input"
ls -> Ok ls
commonFactors : List Int -> List Int
commonFactors ils =
case ils of
[] -> []
ls ->
let l = L.minimum ls
g = L.maximum ls in
case Mb.map2 (\a b -> a == b) l g of
Nothing -> []
Just same ->
case l of
Nothing -> [] -- impossible but have to
Just jl ->
if same then
-- note: modBy has opposite order of arguments
-- when compared to most of other language
L.filter (\dv -> modBy dv jl ==0) (L.range 1 jl)
else
L.filter (\dv ->
L.all (\i ->
modBy dv i == 0) ls)
(L.range 1 jl)
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